Radio relaying



2 Sheets-Sheet lV H. TUNICK RADIO RELAYING Original. Filed June 16, 1942 H.. TuNlcK RADIO RELAYING Sept. 3, 1946.

Original Fild Juge 16, 19424 2 Sheets-Sheet 2 ATTORNEY Patented Sept. 3, 1946 RADIO RELAYING Harry Tuniek, Rye, N. Y., assigner to Radio Corporation of America, a corporation of Dela- Ware Original application June 16, 1942, Serial N0. 447,225. Divided and this application June 13, 1944, Serial No. 540,060

(Cl. Z50-15) 20 Claims. 1 v

This invention is a division of my copending application Serial N o. 447,225, led June 16, 1942. Figures 1, 2, and 3 herein are, respectively, original Figures 5, 6, and 'l of my parent application as filed in the United States Paten-t Olice.

Generally, my present invention relates to conversion of Waves of one frequency to waves of another frequency. My invention has particular application to radio relaying systems for relaying frequency or phase modulated waves or, more generally, angle modulated waves.

One object of my present inven-tion is to provide an improved relay for angle velocity modulated waves in which the received waves are converted to waves of different frequency and retransmitted. The conversion is accomplished with a minimum of distortion. Also, arrangements are provided whereby the retransmitted waves are maintained at a fixed frequency diferup in frequency with waves derived from the same oscillator producing the intermediate frequency. In this way driftsV in frequency of the local oscillator are cancelled out and a frequency for retransmittal is obtained which does not depend upon the use of any freely oscillating oscillator at the relaying point. The frequency difference between the received and retransmitted waves, therefore, is maintained at a definite value depending upon, in the main, the frequency of the received waves.

In the event that it is desired to retransmit with the same deviation as received, I have provided instrumentalties whereby this may be accomplished without an objectionable amount of mean frequency drift and with substantial freedom from distortion.

Other modifications, features, advantages, and objects of my invention will be apparent as the more detailed description thereof proceeds.

In the accompanying drawings:

Figure l illustrates an arrangement wherein the difference between the retransmitted waves and the received waves is derived by frequency multiplying intermediate frequency waves;

Figure 2 illustrates an arrangement enabling the use of frequency multiplication in a relaying system without unduly expanding the frequency deviation in the retransmitted angular velocity modulated waves; and

quency of, for example, 600 megacycles is received on a receiving antenna 500 and with or Without amplification is fed to a converter 502 also supplied with waves from a local generator 504.

The difference frequency is amplified in an intermediate frequency amplier 506 and, as indicated, the difference frequency may be made equal to one megacycle. This intermediate frequency may then be multiplied by a frequency multiplier 508 so that the mean frequency of rthe multiplied energy or waves is three megacycles.

The output of frequency multiplier` 50B, as shown, is fed to a converter 5 l 0 also supplied with waves from oscillator 505i. From the output of converter 5H), filter 5l2 selects either the upper or lower side band, here shown to be the upper side band having a mean frequency of 602 megacycles which is fed to the amplifier 5M and then radiated by radiating antenna 5 l 6.

If desired, of course, 5M may include a frequency multiplier so that the radiated frequency may be some multiple of the output of filter 5l2. For example, if the multiplying factor were chosen to be 3, then the mean frequency radiated by antenna SIE would be 1806 megacycles.

In the relaying system of Figure 2, assume that a frequency modulated wave or a phase modulat ed wave having a mean frequency of 600 mc. is received upon antenna @00. The received wave is fed with or without amplification to a converter 602 also supplied with heterodyning waves having a frequency of 601 megacycles, for example, from local oscillator and frequency multiplier, if desired, 604.

The difference frequency is separated out and amplified by the intermediate frequency amplifier 606 and this wave having a mean frequency of one megacycle for the values chosen is fed to a frequency multiplier 603, One megacycle intermediate frequency waves may be multiplied up to, for example, 4 megacycles by the action of frequency multiplier @t3 and amplied in amplifier Sie, heterodyned to a higher frequency in converter (H2 and filtered and'amplied before retransmission over antenna EIB by means of fil ter 6M and amplifier EIS.

The waves for conversion to a higher frequency are derived from oscillator B94 and filter 620. Filter 620 may be designed so as to have a rather sharp frequency characteristic passing most freely waves having a frequency of 601 mc. for the values of frequency assumed.

Although filter 614 is illustrated to pass 597 mc., it could, of course, be designed to pass the upper side band, namely, 605 mc. which also appears in the output of converter 6 I2.

The action of frequency multiplier 608 serves to multiply the frequency deviation in the retransmitted waves as compared to the frequency deviation representative of the signal in the received waves. If it is desired to retransmit with substantially the same deviation as that received and yet employ the frequency multiplier 608, part of the intermediate frequency output derived fi'om intermediate frequency amplifier 606 may be fed through line 622 to a discriminator and signal demodulator 624 which may be of the type described in Patent No. 2,121,103 to S. W. Seeley.

The demodulated signal may then be fed through line 626 to a reactance tube modulator 628 for modulating the local oscillator 604 in such a way as to reduce the frequency swing in the output of intermediate frequency amplifier 006.

The reactance tube modulator circuits in the rectangle 628 for controlling or frequency modulating the oscillator 604 may use the principles of operation and the circuits shown in the patent to M. G. Crosby No. 2,279,659. The principles of reducing frequency swing by appropriately frequency modulating the heterodyning oscillator 664 are described in greater detail in my copending application Serial No. 423,763, filed December 20, 1941, now U. S. Patent No. 2,362,000.

By appropriately choosing the time constants in circuit 624, this apparatus may be used to automatically frequency control oscillator 604 without a substantial reduction in frequency swing, if desired, in order to insure that the intermediate frequency waves fall within the pass band of the intermediate frequency amplifier 606. In either event, where apparatus 624 is used for this automatic frequency controlling function or for reducing the frequency swing, connection 622 may, if desired, be coupled to the output circuit of amplifier 6|6.

Also, it is to be noted that with conductor 622 fed with a part of the output of amplifier EIS apparatus 624 and 628 may be designed in accordance with the principles set forth in my copending application Serial No. 310,495, filed December 22, 1939, now United States Patent 2,296,- 962, dated September 29, 1942, whereby the retransmitted signal is maintained substantially within an assigned channel despite any tendency towards overmodulation.

In the modification of my invention illustrated in Figure 3, let it be assumed that the incoming Wave received by antenna 100 has a mean frequency of 474 megacycles and that the frequency swing produced by the strongest signal is plus and minus 6 megacycles. The received waves with or without amplification are converted in converter 102 to, for example, a lower, readily arnpliable intermediate frequency such as 100 mc. and fed to the intermediate frequency amplifier 104. The output of intermediate frequency amplifier 104 is then heterodyned up to a converter B-with, for example, a heterodyning Wave of 364 mc. received through line 108. -Filter 110 may select from the output of converter 106 a wave frequency of, for example, 464 megacycles which may be amplified in amplifier 1|2 and then radiated. Or, if desired, the output of amplier 112 may be fed to -a further frequency multiplier 1|4, for example, a doubler, further amplified by amplifier 1 I6 and then radiated over retransmitting antenna 118.

Both of the local oscillators 120, 124 supplying heterodyning waves of 374 mc. and 364 mc., respectively, to the converters 102 and 106 are automatically frequency controlled by fundamental or harmonic frequency waves derived from a common crystal controlled oscillation generator 126.

The automatic frequency control system for oS- cillator 120 consists of converter 123, discriminator circuits 130, balanced detectors 132 and reactance tube frequency control circuits 134. The latter may be replaced, if desired, by a motordriven reactance. As indicated, converter 128 is supplied with Waves from oscillator 120 through line 136 and with waves of fundamental or harmonic frequency through line 138, energized by oscillator 126 or a frequency multiplier associated therewith.

The automatic frequency control system for oscillator 124 is similar and includes the converter 140, discriminator circuit 142, balanced detector 144 and reactance tube circuits or a motor-driven reactance arrangement 146. Converter 140 is fed through line 148 with waves from the oscillator 124 and through line 150 with waves of fundamental frequency or of some harmonic frequency derived from local oscillator 126.

Since both automatic frequency controlling systems are under control of a single local oscillator 126, it will be found that high frequency stability and operation within an assigned chan- .nel will be insured over long periods of time.

In the event that frequency multiplier 114 increases the deviation to an undesired amount, this effect can be reduced by feeding part of the output of the intermediate frequency amplifier 104 to a signal discriminator and demodulator 110, the output of which is used to drive either or both the'reactance tube frequency modulators 112 and 114. Reactance tube frequency modulator 112 is used to frequency modulate the oscillator 120 in such a direction as to reduce the effect of frequency swing in the intermediate frequency amplifier 104. The modulator 114 is used to frequency modulate oscillator 124 in such a direction as to reduce the frequency swing in the output of filter 110. The principles of swing reduction are explained more iully in my copending application Serial No. 423,763, led December 20,

1941, now United States Patent 2,362,000, dated Nov. 7, 1944.

If oscillators 120 and 124 are designed so as to be sufficiently stable, automatic frequency controlling apparatus 134, 136, 132, 130, 128, 138,

150, 140, 142, 144, 146, and 140 may be omitted.

To further insure that the retransmitted Waves lie Within an assigned channel and to prevent over-modulation apparatus 190 may be provided, the output voltage of which may be applied to the frequency modulator 114 or to an independent frequency modulator or frequency control device such as a motor-driven reactance 192. Overmodulation apparatus 190 is more fully described in my copending application Serial No. 310,495,

filed December 22, 1939, now United States Patent 2,296,962, dated Sept. 29, 1942, and generally comprises two circuits tuned to or beyond the extreme frequencies of the assigned channel.

The outputs of these circuits are lfed to detectors which produce rectified currents representative of over-modulation. The outputs of the detectors may then be fed through conductor 194 to, for example, a motor for changing the setting of. a reactance or to a reactance tube in order thereby to change the frequency of oscillation of. local oscillator 124. The frequency controlling apparatus, namely, the reactance tubeor motor-driven reactance device is diagrammatically illustrated at 192. A similar-device may be provided for oscillator 120 driven in parallel by the voltage ap.- pearing in conductor 1,94.

The frequency multipliers referred toY hereinabove may be set `uprin accordance with the principles set forth in the. patent to C. W. Hansell, No. 1,878,308'. The vreactance tube. frequency control' circuitsmay follow the-principlesset forth in the patents to G. Crosby, Nos. 2,227,659, 2,227,660, and 2,227,661. Amplitude limiting may not only be used in the final amplifier stages, but may also be used in the intermediate frequency amplifiers and in the initial amplifiers connected to the receiving antennas as well.

It is to benoted that the over-modulation control system of Figure 3 may, if desired, be of the type described by H. E. Goldstine in his U. S'. Patent'No. 2,296,919. The over-modulation control'is preferably applied to oscillatory 120- so that in the intermediate frequency amplifier 1.04. the effective swing is reduced.

I claim:

1. The method which includes heterodyning electrical waves down to an intermediate frequency, frequency multiplying the waves 'of intermediate frequency .and heterodyning the 'frequency' multiplied waves to a wave of highery fre-l quency.

2. A radio relaying system comprising means for receivedradio waves, a source of oscillations', means for heterodyning the received' Waves to" an intermediate frequency with waves derived fromv said source, a frequency multiplier for frequency multiplying the waves of intermediate frequency', and means for heterodyning the frequencyfmultiplied waves with other waves derived from said local oscillator'.

3. The method which includes heterodyningto an'intermediate frequency Waves of varying frequency, reducing the variations in frequency in said waves of intermediate frequency, vand frequency multiplying' said waves' having said reduced frequency' Variations.

4. TheA method which includes heterodyning frequency modulated waves to a convenient in'- termediate frequency, reducing the frequency l swing of the waves of intermediate frequency, frequency multiplying the waves of intermediate frequency having the reduced swing, and heterodyning the frequencymultiplied waves to a higher frequency.

5. In combination, a source of waves, means for heterodyning said Waves to an intermediate frequency, said heterodyning means comprising an oscillation generator, means for heterodyning said intermediate frequency Waves to still another frequency, saidA last-mentioned means comprising another oscillation generator, and means for automatically frequency controlling said oscilla.- tion generators, said automatic frequency controlling means comprising a. common source of oscillations of substantially constant frequency.

6. The method of relaying frequency modulated waves 'which includes heterodyning the waves to an intermediate frequency, reducing' the frequency swing inthe waves of intermediate freheterodyning the waves 'of reduced swing to a' higher frequency, reducing the frequency swing of the Waves of said higher frequency, and frequency multiplying' said last-mentioned waves.

8. A radio relay system'com'prising an antenna for receiving a radio signal to be. relayed, a local generator, a converter in which said received waves and Waves from said generator are combined to produce waves of a relatively low intermediate frequency, a frequency multiplier for frequency multiplying said waves of intermediete frequency, a second converter for combining the frequency multiplied waves and waves from said generator, anda second antenna for transmitting Waves under control of the output of said second converter.

9. The 4'method' of relaying phase or frequency modulated Waves which includes receiving such modulated waves, generating local oscillations, heterodyning the received Waves with a portion of said locally generated waves so as to produce intermediate frequency waves of relatively low frequency, frequency multiplying said intermediate frequency waves, heterodyning said frequency multiplied waves with another portion of'saidlocally generated Waves to a relatively high frequency, filtering and amplifying said relatively high" intermediate frequency Waves, and reradiatng said: ltered and amplified waves.

l0.m The method of` relaying received phase or frequency modulated high frequency Waves which includes receiving said waves, heterodyning the waves down to arelatively low intermediate frequency, discriminating and detecting a portion of said intermediate frequency Waves, utilizing said detected wavesto reduce the frequencyv or phase deviation of 'said relatively low intermediate frequency waves,` frequencyy multiplying the waves of reduced frequency or phase deviation, heterodyningthe waves of reduced deviation to a higher frequency, filtering'lthe heterodyned Waves, and utilizing the'ltered waves.

il. Apparatus for relaying phase or frequency 50 modulated waves, comprising a local generator ofbscill'ations, a converterto which waves from saidgenerator and received waves are fed and heterodyned together to produce an intermediate frequency Wave, an intermediate frequency ampli- A55 fier forF amplifying said intermediate frequency wave, discriminator-detector apparatus coupled to tlie output of said intermediate frequency amplifier for discriminating and detecting a portion thereof, a frequency modulator for utilizing v the' output of` 'saiddiscriminator-detector apparatusfto frequency' modulate wave energy derivedfroi'n said local" generator which is fed to said' converter, a frequency changer coupled to saidintermediate frequency amplifier for changing the mean frequency of another portion of the Wave. output! of said intermediate frequency amplifier, heterodyning apparatus for heterodyning the output of said frequency changer to a' higher frequency, and circuits for utilizing the v energy of higher frequency.

l2. A relaying system for phase or frequency modulated waves comprising a receiving antenna, a converter' to which waves received by said antenna are fed; a source of local oscillations, circui-tsr' for; feeding waves from said local Source to said converter whereby iwaves of intermediate frequency are produced by said converter, an intermediate frequency amplifier for amplifying waves of intermediate .frequency produced by said converter, discriminator-detector apparatus for discriminating and detecting a portio-n of the 'output of said intermediate frequency amplifier,

a frequency modulator responsive to the output of said discriminator-detector apparatus for frequency modulating said'locally generated Waves in such a direction as to reduce the effective `deviation of waves appearing in the output of said intermediate frequency amplifier, a frequency multiplier for -frequency multiplying the waves of reduced deviation, apparatus for heterodyning the output of said frequency multiplier with wave energy derived from said local generator to a relatively high frequency, apparatus for filtering said relatively high frequency wave energy, and a radiating antenna for radiating waves derived from said filtered relatively high frequency waves. l

13. Apparatus for relaying phase or frequency modulated waves comprising means for receiving waves, a local generator of oscillations, a converter to which waves from said generator and Waves derived from said receiving means arejfed and heterodyned together to produce an intermediate frequency wave, a reactance tube modu lating circuit connected to said generator, an intermediate frequency amplifier for amplifying said intermediate frequency Wave produced by said converter, a second local generator of oscillations, a mixer in which waves from said intermediate frequency amplier and from said second local oscillation generator are mixed to produce waves of relatively high frequency, a second reactance tube frequencycmodulator connected to said second local generator of oscillations, means for operating said reactance tube frequency modulators whereby oscillations generated by said local generators are frequency modulated, filtering apparatus coupled to theoutput of said mixer, and transmitting apparatus for transmitting the output of said lter. Y

14. Apparaus as claimed in the preceding claim. characterized by the provision of a frequency multiplier connected intermediate said mixer and transmitting apparatus.

15. Radio relaying apparatus for -phase or frequency modulated waves comprising means for receiving waves to be relayed, a source of heterodyning oscillations, a first mixer in which waves derived from the received Waves and Waves derived from said source are-combined to produce a wave of intermediate frequency, a frequency multiplier for frequency multiplying the Waves of intermediate frequency, a converter coupled to said frequency multiplier, a second source of local oscillations, means for connecting said secondy source to said converter, transmitting apparatus for transmitting waves derived from the output circuit of said converter, a discriminator-demodulator system connected to said transmitting apparatus, and means for connecting the output of said discrminator-demodulator system to one of said local oscillation generators in such a Way as to control and vary the frequency thereof.

16. Apparatus for relaying phaseor frequency modulated Waves comprising means for receiving waves, a local generator of oscillations, a converter to-Which Waves from said generator and waves derived from said receiving means are fed and heterodyned together to produce an intermediate frequency Wave, a reactance tube-modu-l lating circuit connected to said generator, an intermediate frequency amplifier for amplifying said intermediate frequency wave produced by said converter, a second local generator of oscillations, a mixer in which waves from said intermediate frequency amplifier and from said second local oscillation generator are mixed to produce waves of relatively high frequency, a second reactance tube frequency modulator connected to said second local generator of oscillations,'a source of control potentials, means for connecting said reactance tube frequency modulators to said source of control potentials whereby oscillations generated by said local generators are varied in frequency in accordance with said control potentials, filtering apparatus coupled to the output of said mixer, and transmitting apparatus for transmitting the output of said filter.

17. Radio yrelaying apparatus for phase or frequency rrnodulatedwaves comprising means for receiving Waves to be relayed, a source of heterodyning oscillations, a rst mixer in which waves derived from the received Waves and waves derived from said source are combined to produce a wave of intermediate frequency, an amplier for amplifying said wave of intermediate frequency,a converter coupled tosaid amplifier, a second source of local oscillations, means for connecting said second source to said converter, transmitting apparatus for transmitting waves derived from the output circuit of said converter. a dlscriminator-demodulator system connected to said transmitting apparatus, and means for connecting the output of said discriminator-demodulator system to one of said local oscillation generators in such a Way as to control and vary the frequency thereof.

, 18. Apparatus for relaying phase or frequency modulated Waves comprising means for receiving Waves, a local generator of oscillations,l a converter to which Waves from said generator and waves derived from receiving means are fed and heterodyned together to produce an intermediate frequency wave, a reactance tube modulating circuit connected to said generator, an intermediate frequency amplifier for amplifying said'intermediate frequency wave produced by said converter, a second local generator of oscillations, a mixer in which Waves from said intermediatefrequency amplifier and from said second local oscillation generator are mixed to produce waves of relatively high frequency, a second reactance tube frequency modulator connected to said second local generator of oscillations, means for producing modulating Waves, means for connecting said last-mentioned means for producing modulating waves to said frequency modulators whereby `oscillations generated by said local generators are frequency modulated, means for filtering the output of said mixer, and transmitting apparatus for transmitting the output of said ltering means.

19. Apparatus for relaying phase or frequency modulated waves comprising means for receiving waves, a local generator of oscillations, a converter to which waves from said generator and waves derived from said receiving means are fed and heterodyned together to produce an intermediate frequency wave, an intermediate frequency amplifier for amplifying said intermediate frequency Wave produced by said converter, a second local generator of oscillations, a mixer in which waves from said intermediate frequency amplifier and from said second local oscillation 7D generator are mixed to produce waves of relative1y high frequency. a reactance tube frequency modulator connected to one of said local genera.- tors of oscillations, means responsive to modulating waves for operating said reactance tube frequency modulator whereby oscillations generated by said local generator to which said modulator is connected are frequency modulated, filtering apparatus coupled to the output of said mixer, and transmittingl apparatus for transmitting the output of said filtering apparatus.

20. Apparatus for relaying phase or frequency modulated Waves comprising means for receiving waves, a local generator of oscillations, a converter to Which Waves from said .generator and waves derived from said receiving means are fed and heterodyned together to produce an intermediate frequency wave, an intermediate frequency amplifier for amplifying said intermediate frequency wave produced by said converter,y

a second'local generator of oscillations, a mixer in which Waves from said intermediate frequency amplifier and from' said second local oscillation generator are mixed to produce Waves of relatively high frequency, a frequency modulator circuit connected to one of said generators of oscillations, means responsive to modulating potentials for operating said frequency modulator circuit Whereby oscillations generated by said local generator to which said modulator circuit is connected are frequency modulated, and transmitting apparatus connected to the output circuit of said mixer.

HARRY TUNICK. 

